In the year 1949 the Derby Cookbook was published in a brown hardback binding. The first edition came for the publisher named Doubleday.
If one searches on Amazon.com (the largest online bookseller) the 1949 Brown Derby Cookbook can be bought at prizes ranging from about $65 and upwards to over $200 depending on the state of the book.
Another place that you can search for this particular cookbook is at eBay.com. If you're not familiar with purchasing on eBay I suggest that you spend a little time before you buy the cookbook from a complete stranger
A third option that you have to find the 1949 Brown Derby Cookbook is to visit your local library. They might not have it available but they'll gladly search their databases to find you a copy that you can borrow.